I have an '07 Sirrus that is bone stock with a Shimano Sora drive train. It seems like in compared to my older 6 speeds (Shimano 105 and Deore) it has no durability. I replaced the chain and rear cogset at 853 miles and it had begun slipping again after 400 miles. The bikes that have 105 and Deore ran their original drivetrain for YEARS before the Deore drive train needed chainwheels and a cogset. Is my story unique? I'm lubing my chain with Triflow and flushing it out and relubing every third ride. I also used Pedro's Ice Wax for a time, but went back to Triflow as it seems to last longer..